U.S. patent application number 12/092221 was filed with the patent office on 2009-09-17 for multistage compressor for a gas turbine, comprising discharge ports and injection ports to stabilize the compressor flow.
Invention is credited to Frank Grauer.
Application Number | 20090232636 12/092221 |
Document ID | / |
Family ID | 37866141 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090232636 |
Kind Code |
A1 |
Grauer; Frank |
September 17, 2009 |
MULTISTAGE COMPRESSOR FOR A GAS TURBINE, COMPRISING DISCHARGE PORTS
AND INJECTION PORTS TO STABILIZE THE COMPRESSOR FLOW
Abstract
A multistage compressor for a gas turbine, having a compressor
housing, guide vanes, impeller vanes, a hub area, discharge ports,
and injection ports for stabilizing the compressor flow, wherein
the discharge ports are situated at least one stage downstream from
the injection ports, the injection ports being fashioned as
nozzles, and the geometry of these nozzles is designed such that
the flow speed of the injected air stream is significantly greater
than the speed of the flow in a critical cross-section.
Inventors: |
Grauer; Frank; (Karlsfeld,
DE) |
Correspondence
Address: |
GREER, BURNS & CRAIN
300 S WACKER DR, 25TH FLOOR
CHICAGO
IL
60606
US
|
Family ID: |
37866141 |
Appl. No.: |
12/092221 |
Filed: |
October 26, 2006 |
PCT Filed: |
October 26, 2006 |
PCT NO: |
PCT/DE06/01889 |
371 Date: |
July 29, 2008 |
Current U.S.
Class: |
415/58.5 |
Current CPC
Class: |
F04D 29/545 20130101;
F04D 19/028 20130101; F04D 29/681 20130101; F01D 5/145 20130101;
F04D 29/682 20130101; F04D 29/321 20130101; Y02T 50/673 20130101;
F04D 27/0207 20130101; F04D 27/0238 20130101; F04D 29/684 20130101;
Y02T 50/60 20130101 |
Class at
Publication: |
415/58.5 |
International
Class: |
F01D 25/24 20060101
F01D025/24 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 3, 2005 |
DE |
10 2005 052 466.4 |
Claims
1. A multistage compressor for a gas turbine, having a compressor
housing, guide vanes, impeller vanes, a hub area, discharge ports,
and injection ports for stabilizing the compressor flow,
comprising: the discharge ports are situated at least one stage
downstream from the injection ports, the injection ports being
fashioned as nozzles, and the geometry of these nozzles being
designed such that the flow speed of the injected air stream is
significantly greater than the speed of the flow in a critical
cross-section.
2. The multistage compressor for a gas turbine as recited in claim
1, wherein the discharge ports and the injection ports are situated
in the compressor housing.
3. The multistage compressor for a gas turbine as recited in claim
1, wherein the discharge ports and the injection ports are situated
in the hub area.
4. The multistage compressors for a gas turbine as recited in claim
1, wherein the discharge ports are situated in the compressor
housing, and the injection ports are situated in the hub area, or
the discharge ports are situated in the hub area and the injection
ports are situated in the compressor housing.
5. The multistage compressors for a gas turbine as recited in claim
1, wherein devices are provided for recognizing critical operating
conditions.
6. The multistage compressors for a gas turbine as recited in claim
1, wherein the injection ports are fashioned as nozzles.
7. The multistage compressor for a gas turbine as recited in claim
6, wherein the nozzles have a variable cross-section.
8. The multistage compressor for a gas turbine as recited in claim
1, wherein fast-opening valves are provided at the injection
ports.
9. The multistage compressor for a gas turbine as recited in claim
1, further including a valve controlling is provided for the
continuous, modulated, or pulsed injection of air into the
injection ports.
10. The multistage compressor for a gas turbine as recited in claim
1, wherein the discharge ports are situated in a high-pressure
compressor or in a medium-pressure compressor, and the injection
ports are situated in a fan or in a low-pressure compressor.
Description
[0001] The present invention relates to a multistage compressor for
a gas turbine, having a compressor housing, guide vanes, impeller
vanes, a hub area, discharge ports and injection ports in order to
stabilize the compressor.
[0002] In gas turbines, the compressor is designed for particular
flight states. For these design points, the compressor must achieve
the pre-calculated characteristic values such as throughput
pressure ratio, efficiency, etc. In addition, however, the
compressor must also have acceptable and safe operating
characteristics within a broad range of rotational speeds beyond
the design points. This part load behavior, or also transient
behavior, in which the full propulsion power is not demanded, is
particularly important in aircraft engines, e.g. during the landing
approach of an airplane, where for example rapid changes in thrust,
and thus rapid changes in rotational speed, are required in order
to maintain the aircraft's glideslope. However, when the engine is
being started up, i.e. in the lower rotational speed range, the
compressor must provide problem-free flow and enable the engine to
be rapidly run up to full load.
[0003] In order to determine the part load behavior, a compressor
characteristic field is measured with which the reliable operating
range around the design point is determined along what is called a
trajectory. The trajectory connects operating points on different
rotational speed lines, and has a sufficient safety distance from
what is called the pump limit. The stall at the compressor vanes is
called pumping, or surge.
[0004] In the characteristic field of a compressor, operating
regions can be identified that are critical under certain
circumstances with respect to the existing pump limit distance,
e.g. transient maneuvers of an aircraft driven by the gas turbine.
These briefly existing operational states are decisive for the
determination of the pump limit distance that is to be maintained
in the design.
[0005] In principle, it is known that the injection of air into the
housing area of a compressor can under certain conditions shift the
pump limit to lower throughputs. In the literature, various
interventions are known for stabilizing compressors, including for
example the discharge of compressor air through discharge valves,
known as bleed valves, injection of air via recirculation,
adjustment of variable guide vanes in the compressor, or modulation
of the fuel supply. In most cases, the intervention is initiated by
an advance notification, not described in more detail, of a
possible instability. In most published references, for this
purpose pressure measurements are provided at various points in a
compressor as input quantities for a regulating system.
[0006] U.S. Pat. No. 5,607,284 discloses a compressor housing
having recirculation ducts. In the vane tip covering of an impeller
vane stage, there is situated an annular segment that has discharge
ports on the side of the vane situated downstream and injection
ports on the side of the vane situated upstream. The discharge and
injection ports are connected by ducts that are interrupted by flow
guide elements. In this way, a continuous unregulated backflow is
produced that is intended to prevent stall and the pumping
connected therewith. An example of a corresponding arrangement is
shown schematically in FIG. 3.
[0007] FIG. 3 shows a system of a compressor 1 known from the prior
art. Discharge port 5 and injection port 4 are situated on the same
stage, i.e., here over the same impeller vane 6. Valves or nozzles
are not present here. There is also no regulation of the injected
air or of the injection process. Rather, a permanent recirculation
of the air is produced via a stage, connected with the
corresponding losses.
[0008] On the one hand, in this system it is disadvantageous that
the continuous backflow also means that losses of efficiency have
to be accepted, even though there is no danger of pumping.
Moreover, the recirculation of the flow to the same stage often
does not supply enough energy-rich flow, so that under particularly
critical operating conditions this solution alone is not sufficient
to prevent pumping.
[0009] The object of the present invention is therefore to avoid
the above-named technical problems in the prior art, and to provide
an improved solution that achieves significant improvements with
respect to efficiency and reduced engine weight.
[0010] According to the present invention, this object is achieved
by the features of patent claim 1. Advantageous specific
embodiments and developments of the present invention are indicated
in the subclaims.
[0011] The present invention solves the problems of the prior art
and enables significantly improved efficiency and reduced engine
weight.
[0012] According to the present invention, a multistage compressor
for a gas turbine is provided having a compressor housing, guide
vanes, impeller vanes, a hub area, discharge ports, and injection
ports for stabilizing the compressor flow, characterized in that
the discharge ports are situated at least one stage downstream from
the injection ports.
[0013] This makes it possible to achieves significant improvements
with regard to efficiency and engine weight, because the compressor
can be designed with a pump limit distance that a small enough that
it can be stably operated in stationary operation, and the pump
limit distance can be ensured through a regulating intervention
that is brief in critical operating conditions.
[0014] The majority of critical operating states occur in the
transient area, when the compressor is operated in part load
operation. In this operating range, normally the front stages
determine the stability, because here the flow is first separated
and the compressor begins to pump. The solution to the present
invention provides that during an operating state recognized as
critical, air with sufficiently high pressure is tapped from one of
the rear compressor stages, and is reinjected before or via the
stage causing the instability with a high excess speed in the
critical cross-section of the front stages. The pressure difference
between the tap point and the injection point must be selected such
that the required excess speed can be achieved, which is ensured by
a corresponding stage distance between the discharge point and the
injection point. The air can be guided to the front stages via pipe
conduits or hollow spaces in the housing, and can be injected there
via a plurality of ports distributed around the circumference.
[0015] A first advantageous specific embodiment of the present
invention provides that the discharge ports and the injection ports
are situated in the compressor housing. The flow ducts can easily
be routed here.
[0016] A second advantageous specific embodiment of the present
invention provides that the discharge ports and the injection ports
are situated in the hub area, in particular in a hub housing. As a
rule, the feedback of the discharged air takes place here via pipe
conduits.
[0017] A third advantageous specific embodiment of the present
invention provides that the discharge ports are situated in the
compressor housing and the injection ports are situated in the hub
area, or the discharge ports are situated in the hub area and the
injection ports are situated in the compressor housing. The
transition from the compressor housing to the hub area can take
place via conduits situated in guide vanes. It is also possible for
air to blow out from vanes or structural components, in particular
struts, situated upstream from the rear edges.
[0018] An advantageous development of the present invention
provides that devices are provided for recognizing critical
operating conditions. The device for recognizing critical operating
conditions can be activated via an algorithm for recognizing these
states, or by a pre-controlling in the case of maneuvers that can
be recognized independently by the system or by an engine model
that runs concomitantly in real time, such as engine accelerations
or slams. In addition, corresponding sensors can also be used,
which can be used as inputs for a corresponding regulating
system.
[0019] An advantageous development of the present invention
provides that the injection ports are fashioned as nozzles. Here,
the nozzles are situated such that the air is injected into the
annular space as close as possible to parallel to the flow. The
geometry of the nozzles is designed such that the flow speed of the
injected air stream is significantly greater than the speed of the
flow in the critical cross-section.
[0020] An advantageous development of the present invention
provides that the nozzles have a variable cross-section. This
ensures the effectiveness of the injection in a wide operating
range. The variable elements can be either regulated or set in a
controlled manner via various actuating elements. Possible
actuators include piezoelement, MEMS components, shape-memory
alloys, or conventional electrical or hydraulic or pneumatic
elements.
[0021] An advantageous development of the present invention
provides that fast-opening valves are provided at the injection
ports. This keeps the reaction time of the overall system low.
[0022] An advantageous development of the present invention
provides that a valve controlling is provided for the continuous,
modulated, or pulsed injection of air into the injection ports.
Here, continuous means that injection takes place simultaneously
from all injection points distributed around the circumference. In
a modulated injection, the injection points distributed around the
circumference are differently controlled in order for example to
produce an injection stream that circulates in the annular space.
In pulsed injection, each valve is opened and closed with a fixed
frequency.
[0023] An advantageous development of the present invention
provides that the discharge ports are situated in a high-pressure
compressor or in a medium-pressure compressor, and the injection
ports are situated in a fan or a low-pressure compressor. This
ensures that sufficiently energized flow is always injected.
[0024] Further measures that improve the present invention are
explained in more detail in the following, together with the
description of a preferred exemplary embodiment of the present
invention on the basis of the Figures.
[0025] FIG. 1 shows a schematic representation of a first specific
embodiment according to the present invention;
[0026] FIG. 2 shows a schematic representation of a second specific
embodiment according to the present invention;
[0027] FIG. 3 shows a schematic representation of a known solution
according to the prior art.
[0028] Directional indications relate to the compressor axis,
unless otherwise indicated. Identical or similar components have
been provided with identical reference characters.
[0029] FIG. 1 shows a schematic representation of a first specific
embodiment of a multistage compressor 1 having an axial
construction for a gas turbine, having an essentially annular
compressor housing 2, guide vanes 7 situated on the housing,
impeller vanes 6 situated on a rotor, a hub area 3 that covers the
rotor hub, discharge ports 5 distributed around the circumference,
and injection ports 4, also distributed around the circumference,
for stabilizing compressor 1 according to the present invention.
The flow direction is indicated by a white arrow that runs from
left to right in the plane of the drawing. Discharge ports 5 are
situated at least one stage downstream from injection ports 4,
which are provided with nozzles and fast-opening valves (not
shown).
[0030] As soon as the recognition device (not shown) has
recognized, via a corresponding algorithm or via a pre-controlling,
a critical compressor operating state, i.e. a state of near-pumping
or pumping, discharged air is provided to injection port 4 from the
downstream discharge port via flow ducts (not shown) in compressor
housing 2. The recirculation flow is indicated in the Figure by
corresponding arrows. Through corresponding controlling of the
fast-opening valves at the injection ports, air is injected into
the compressor stage situated upstream with a sufficient pressure
difference, via the nozzles situated in the injection ports. The
controlling of the valves takes place via the recognition device.
In the present exemplary embodiment, piezoelements are used as
actuators, because they have particularly short response times. The
injection of the energy-rich flow into the annular space of the
endangered stage prevents separation of the flow and temporarily
shifts the pump limit. As soon as the critical operating area has
been moved through, the injection valves can be closed again in
order to avoid unnecessarily reducing efficiency.
[0031] FIG. 2 shows a schematic representation of a second specific
embodiment according to the present invention. In contrast to the
first specific embodiment described above, here injection ports 4
and discharge ports 5 are situated in the hub area. The
recirculation thus takes place in the wave area, via pipe conduits
(not shown). The recirculation flow is also indicated by black
arrows. Due to the action of centrifugal force at the injection
opening, the injected air is given an additional speed component.
Otherwise, the functioning and action are comparable to that
described in connection with FIG. 1.
[0032] The realization of the present invention is not limited to
the above-indicated preferred exemplary embodiment. Rather, a
number of variants are conceivable that make use of the present
solution in realizations having fundamentally different
constructions.
* * * * *